242 lines
6.9 KiB
C++
242 lines
6.9 KiB
C++
/**************************************************************************
|
|
* orbits.c - calculates the orbital elements of the sun, moon and planets.
|
|
* For inclusion in flight gear
|
|
*
|
|
* Written 1997 by Durk Talsma, started October 19, 1997.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License as
|
|
* published by the Free Software Foundation; either version 2 of the
|
|
* License, or (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
|
*
|
|
* $Id$
|
|
* (Log is kept at end of this file)
|
|
**************************************************************************/
|
|
|
|
|
|
#ifdef HAVE_CONFIG_H
|
|
# include <config.h>
|
|
#endif
|
|
|
|
#include <math.h>
|
|
#include <string.h>
|
|
|
|
#include <Debug/fg_debug.h>
|
|
#include <Include/fg_constants.h>
|
|
#include <Include/general.h>
|
|
#include <Time/fg_time.hxx>
|
|
|
|
#include "orbits.hxx"
|
|
|
|
|
|
struct OrbElements pltOrbElements[9];
|
|
|
|
|
|
double fgCalcActTime(struct fgTIME t)
|
|
{
|
|
return (t.mjd - 36523.5);
|
|
}
|
|
|
|
|
|
double fgCalcEccAnom(double M, double e)
|
|
{
|
|
double
|
|
eccAnom, E0, E1, diff;
|
|
|
|
eccAnom = M + e * sin(M) * (1.0 + e * cos(M));
|
|
/* iterate to achieve a greater precision for larger eccentricities */
|
|
if (e > 0.05)
|
|
{
|
|
E0 = eccAnom;
|
|
do
|
|
{
|
|
E1 = E0 - (E0 - e * sin(E0) - M) / (1 - e * cos(E0));
|
|
diff = fabs(E0 - E1);
|
|
E0 = E1;
|
|
}
|
|
while (diff > (DEG_TO_RAD * 0.001));
|
|
return E0;
|
|
}
|
|
return eccAnom;
|
|
}
|
|
|
|
|
|
/* This function assumes that if the FILE ptr is valid that the
|
|
contents will be valid. Should we check the file for validity? */
|
|
|
|
/* Sounds like a good idea to me. What type of checks are you thinking
|
|
of, other than feof(FILE*)? That's currently the only check I can
|
|
think of (Durk) */
|
|
|
|
int fgReadOrbElements(struct OrbElements *dest, FILE *src)
|
|
{
|
|
char line[256];
|
|
int i,j;
|
|
j = 0;
|
|
do
|
|
{
|
|
if (feof (src)) {
|
|
fgPrintf (FG_ASTRO, FG_ALERT,
|
|
"End of file found while reading planetary positions:\n");
|
|
return 0;
|
|
}
|
|
|
|
fgets(line, 256,src);
|
|
for (i = 0; i < 256; i++)
|
|
{
|
|
if (line[i] == '#')
|
|
line[i] = 0;
|
|
}
|
|
/*printf("Reading line %d\n", j++); */
|
|
}
|
|
while (!(strlen(line)));
|
|
sscanf(line, "%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf\n",
|
|
&dest->NFirst, &dest->NSec,
|
|
&dest->iFirst, &dest->iSec,
|
|
&dest->wFirst, &dest->wSec,
|
|
&dest->aFirst, &dest->aSec,
|
|
&dest->eFirst, &dest->eSec,
|
|
&dest->MFirst, &dest->MSec);
|
|
|
|
return(1);
|
|
}
|
|
|
|
|
|
int fgSolarSystemInit(struct fgTIME t)
|
|
{
|
|
fgGENERAL *g;
|
|
char path[80];
|
|
int i;
|
|
FILE *data;
|
|
int ret_val = 0;
|
|
|
|
fgPrintf( FG_ASTRO, FG_INFO, "Initializing solar system\n");
|
|
|
|
/* build the full path name to the orbital elements database file */
|
|
g = &general;
|
|
path[0] = '\0';
|
|
strcat(path, g->root_dir);
|
|
strcat(path, "/Scenery/");
|
|
strcat(path, "Planets.dat");
|
|
|
|
if ( (data = fopen(path, "r")) == NULL )
|
|
{
|
|
fgPrintf( FG_ASTRO, FG_ALERT,
|
|
"Cannot open data file: '%s'\n", path);
|
|
} else {
|
|
/* printf(" reading datafile %s\n", path); */
|
|
fgPrintf( FG_ASTRO, FG_INFO, " reading datafile %s\n", path);
|
|
|
|
/* for all the objects... */
|
|
for (i = 0; i < 9; i ++)
|
|
{
|
|
/* ...read from the data file ... */
|
|
if (!(fgReadOrbElements (&pltOrbElements[i], data))) {
|
|
ret_val = 0;
|
|
}
|
|
/* ...and calculate the actual values */
|
|
fgSolarSystemUpdate(&pltOrbElements[i], t);
|
|
}
|
|
ret_val = 1;
|
|
}
|
|
return ret_val;
|
|
}
|
|
|
|
|
|
void fgSolarSystemUpdate(struct OrbElements *planet, struct fgTIME t)
|
|
{
|
|
double
|
|
actTime;
|
|
|
|
actTime = fgCalcActTime(t);
|
|
|
|
/* calculate the actual orbital elements */
|
|
planet->M = DEG_TO_RAD * (planet->MFirst + (planet->MSec * actTime));
|
|
planet->w = DEG_TO_RAD * (planet->wFirst + (planet->wSec * actTime));
|
|
planet->N = DEG_TO_RAD * (planet->NFirst + (planet->NSec * actTime));
|
|
planet->i = DEG_TO_RAD * (planet->iFirst + (planet->iSec * actTime));
|
|
planet->e = planet->eFirst + (planet->eSec * actTime);
|
|
planet->a = planet->aFirst + (planet->aSec * actTime);
|
|
}
|
|
|
|
|
|
/* $Log$
|
|
/* Revision 1.3 1998/04/25 22:06:25 curt
|
|
/* Edited cvs log messages in source files ... bad bad bad!
|
|
/*
|
|
* Revision 1.2 1998/04/24 00:45:01 curt
|
|
* Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
|
|
* Fixed a bug when generating sky colors.
|
|
*
|
|
* Revision 1.1 1998/04/22 13:21:29 curt
|
|
* C++ - ifing the code a bit.
|
|
*
|
|
* Revision 1.10 1998/04/18 04:13:57 curt
|
|
* Moved fg_debug.c to it's own library.
|
|
*
|
|
* Revision 1.9 1998/03/14 00:27:12 curt
|
|
* Updated fgGENERAL to a "type" of struct.
|
|
*
|
|
* Revision 1.8 1998/02/23 19:07:55 curt
|
|
* Incorporated Durk's Astro/ tweaks. Includes unifying the sun position
|
|
* calculation code between sun display, and other FG sections that use this
|
|
* for things like lighting.
|
|
*
|
|
* Revision 1.7 1998/02/12 21:59:33 curt
|
|
* Incorporated code changes contributed by Charlie Hotchkiss
|
|
* <chotchkiss@namg.us.anritsu.com>
|
|
*
|
|
* Revision 1.6 1998/02/03 23:20:11 curt
|
|
* Lots of little tweaks to fix various consistency problems discovered by
|
|
* Solaris' CC. Fixed a bug in fg_debug.c with how the fgPrintf() wrapper
|
|
* passed arguments along to the real printf(). Also incorporated HUD changes
|
|
* by Michele America.
|
|
*
|
|
* Revision 1.5 1998/02/02 20:53:22 curt
|
|
* To version 0.29
|
|
*
|
|
* Revision 1.4 1998/01/27 00:47:47 curt
|
|
* Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
|
|
* system and commandline/config file processing code.
|
|
*
|
|
* Revision 1.3 1998/01/22 02:59:27 curt
|
|
* Changed #ifdef FILE_H to #ifdef _FILE_H
|
|
*
|
|
* Revision 1.2 1998/01/19 19:26:58 curt
|
|
* Merged in make system changes from Bob Kuehne <rpk@sgi.com>
|
|
* This should simplify things tremendously.
|
|
*
|
|
* Revision 1.1 1998/01/07 03:16:17 curt
|
|
* Moved from .../Src/Scenery/ to .../Src/Astro/
|
|
*
|
|
* Revision 1.6 1997/12/30 20:47:52 curt
|
|
* Integrated new event manager with subsystem initializations.
|
|
*
|
|
* Revision 1.5 1997/12/15 23:55:02 curt
|
|
* Add xgl wrappers for debugging.
|
|
* Generate terrain normals on the fly.
|
|
*
|
|
* Revision 1.4 1997/12/10 22:37:51 curt
|
|
* Prepended "fg" on the name of all global structures that didn't have it yet.
|
|
* i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
|
|
*
|
|
* Revision 1.3 1997/11/25 23:20:44 curt
|
|
* Changed planets.dat Planets.dat
|
|
*
|
|
* Revision 1.2 1997/11/25 19:25:36 curt
|
|
* Changes to integrate Durk's moon/sun code updates + clean up.
|
|
*
|
|
* Revision 1.1 1997/10/25 03:16:10 curt
|
|
* Initial revision of code contributed by Durk Talsma.
|
|
*
|
|
*/
|